Battery Remaining Capacity Detection via Multi-Method Weighted Averaging
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Solution Overview
Problem
Existing methods for detecting the remaining capacity of batteries in power supply units, especially in vehicles, face challenges in accurately determining internal resistance and open circuit terminal voltage, leading to inaccuracies in computing the real remaining capacity.
Innovation Solution
A power supply unit equipped with current and voltage detecting portions, and a computing portion that calculates the real remaining capacity by weighted-averaging multiple computed capacities based on integrated current values, open circuit terminal voltages, and considering ohmic and polarization resistances, along with temperature and hysteresis characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the remaining capacity is computed through integrated value by integrating current value, then the computation is simple, but the accuracy deteriorates due to current measurement errors and battery temperature variations
Solution Approach 1:
The patent merges two different computation methods: the current integrated method (simple but inaccurate) and the voltage-based open circuit terminal voltage method (accurate but complex). By combining both approaches and selecting the more accurate result based on predetermined conditions, the system achieves both computational efficiency and high accuracy in remaining capacity detection.
2Measurement precision
If the open circuit terminal voltage is detected through internal resistance, then the remaining capacity can be detected, but the internal resistance detection accuracy deteriorates making the overall measurement inaccurate
Solution Approach 1:
The patent uses the terminal voltage as an intermediary measurement that is easier to detect accurately than internal resistance. Instead of directly measuring internal resistance (which is difficult and inaccurate), the system measures terminal voltage under known current conditions and calculates the open circuit terminal voltage through computation, thereby avoiding the direct measurement problem.
Solution Approach 2:
The patent replaces the direct electrical measurement of internal resistance with a computational approach. Instead of using physical measurement instruments to detect internal resistance, the system uses mathematical calculations based on terminal voltage and current measurements to derive the open circuit terminal voltage and remaining capacity.
3Measurement precision
If multiple computation methods are used to improve accuracy, then the remaining capacity detection precision is improved, but the device complexity increases
Solution Approach 1:
The patent implements a dynamic selection mechanism that adapts the computation method based on predetermined conditions (such as battery state, current magnitude, temperature). The system switches between different computation approaches depending on the operational context, maintaining high accuracy while avoiding unnecessary computational complexity in each specific situation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for accurate detection of the real remaining capacity of batteries, improving the precision of state-of-charge estimation and extending battery life by minimizing over-discharge or over-charge conditions.
Implementation Method 1
A power supply unit 100 supplies electric power to a load 50, or is charged by electric power from a charging power source 51
Implementation Method 2
a current detecting portion 16 detecting charging and discharging current of the battery 22
Implementation Method 3
a voltage detecting portion 12 detecting voltage of the battery 22
Data Source
AI summary
A power supply unit comprises a battery, current and voltage detecting portions, and a remaining capacity computing portion. The remaining capacity computing portion comprises a first computing portion computing a first open circuit terminal voltage based on current and voltage values from the current and voltage detecting portions, and computing a first remaining capacity based on the first open circuit terminal voltage, a second computing portion computing a second open circuit terminal voltage based on the current and voltage values, an ohmic resistance voltage drop and a polarization resistance voltage drop, and computing a second remaining capacity based on the second open circuit terminal voltage, a third computing portion calculating a third remaining capacity based on an integrated value by integrating the current, and a main computing portion computing a real remaining capacity of the battery based on the first and/or third remaining capacity, and the second remaining capacity.